Urethane/urea-containing polythioether prepolymers are known to be useful in aerospace sealant applications. Polythioether prepolymers can be prepared by reacting a polythiol with a divinyl ether to provide prepolymers that provide sealants that meet the demanding performance requirements of the aerospace industry. Examples are disclosed in U.S. application Ser. No. 14/964,904 filed on Dec. 10, 2015, and in U.S. Application Publication Nos. 2015/0252232 and 2015/0252230, each of which is incorporated by reference in its entirety.
For certain aerospace sealants it can also be desirable that the sealant contain a high loading of filler. Filler can be included in a sealant for a number of reasons such as to improve the physical properties of the cured sealant, to reduce the weight, to impart electrical conductivity, and/or to impart RFI/EMI shielding effectiveness. The addition of filler can reduce the tensile strength and elongation of the cured sealant.
Therefore, it is desirable to provide polythioether prepolymers that when used in compositions having a high filler content, exhibit high tensile strength and elongation.